1. Field of the Invention
The present invention relates to a tunneling transistor capable of controlling negative resistance characteristics.
2. Description of the Prior Art
Prior practice of negative resistance devices through tunneling includes a resonant hot electron transistor (RHET) and a resonant tunneling bipolar transistor (RBT), those transistors being constructed through combination of a resonant tunneling structure with a heterojunction bipolar transistor or a field effect transistor. These transistors are successful in the construction Ex-NOR gates, multiple-state holding gates, latch circuits and NOR circuits with a more reduced number of constituent transistors compared with prior art transistors, and hence attracts many interests with the expectation of application to functional devices. These devices are described, for example, in Electron Devices, Vol. 36, p 2065, 1989, F. Capasso, et al.
In the resonant tunneling effect, there is taken as a tunnel barrier the size of a discontinuity of conduction band energy in a semiconductor heterojunction, i.e., a difference between electron affinities between constituting semiconductors, so that the height of the tunnel barrier is not increased and the resonant tunneling effect is severely affected by a current (an excess current) based upon electrons going over the barrier by thermal excitation at room temperature.
The foregoing prior art tunneling transistors are therefore unlikely to be operational at room temperature.